Research Of Electrodeposition Of La-Mg-Ni Alloy Film

Hydrogen storage material has been applied widely in Ni-MH battery and other affairs. With the development of application of hydrogen storage material, it is specially necessary how increases the capacity of hydrogen storage that can be required. A great number of researches show that Ni-MH battery which is added rare earth will obtain higher capacity, longer cycle life and lower cost.The La-Mg-Ni system? hydrogen storage alloy has a perfect application foreground that can be used as the cathode of Ni-MH battery,because of its high capacity and good activation performance.Presently,La-Mg-Ni system hydrogen storage alloy as powder-like or piece-like in shape can be made by melting,mechanize or burning knot. However, these methods have high cost and complicated equipment. Electrodeposition method can obtain film that is used as electrodes.In this paper,La-Mg-Ni alloy film was prepared by electrodeposition of potentiostatic in low temperature rong salt that was constituted with acetamide,carbamide and sodium bromide,and in aqueous media,by potentiostatic,galvanostatic and impulse method?both from home and abroad.By means of cyclic voltammetry(CV),Tafel polarization curve and electrochemical impedance spectroscopy(EIS),electrochemical performance of the alloy film was studied.Sanning electronic microscope(SEM),energy distribution spectrum(EDS) and X-ray diffractometer(XRD) were used to research the phase structure,component and composition.The results showed that the characteristic peak of electrodeposited alloy films can be seen from the XRD patterns, which has strong LaMg2Ni9 peaks. The film has better hydrogen storage function and neat degree,with the cathode potential shifts to negative direction, the value obtained for the apparent energy of activation and the constant phase angle of adsorption are 22.51 kJ·mol^-1 and 7.98μF/cm2,when the voltage is ^-1.0V in the rong salt;the film has better hydrogen storage function and the cracks become big with the cathode potential shifts to negative direction in the neighborhood of electrodeposition,potential and the electric current density increasing of the La and Mg. The film of La-Mg-Ni alloy was prepared by constant-current electrodeposition method in aqueous media. When the current is 30 A·dm^-2, the value obtained for the apparent energy of activation is the least(31.88 kJ·mol^-1). The Ni is able to be prepared when the he voltage shift negative from -0.5V,the the value obtained for the apparent energy of activation is the minimum on the -0.7V voltage in aqueous media( G≠=22.25 kJ·mol^-1);with the current density increasing, the surface of the film is rougher, and the hydrogen corrosion current density increases.With the average current density of 0.33A/cm2,the duty cycle of 25% and pulse rate of 150Hz,the La-Mg-Ni alloy film which the value obtained for the apparent energy of activation is 23.15 kJ·mol^-1 and the constant phase angle of adsorption is 8.08μF·cm^-2 has the best performance of hydrogen.